When I run a DC sim with a swept DC voltage, such as a gate voltage, and then I plot a current, the plot puts the current on the y-axis and the swept DC voltage on the x-axis. Is there any way to apply calculations to the x-axis (swept DC parameter) the way that you can with the y-axis data? For example, when I sweep the gate voltage on a PMOS device, I would rather plot Ids versus Vg-VDD instead of Vg with respect to ground.
Does anyone know if this is possible?
After the simulation completes and the DC results are plotted, do the following:
1. Open the Calculator and create an expression for the x-axis quantity. E.g. VS("/gate") - VS("/vdd").
2. Make sure the plot mode is set to "append" and plot the expression. The expression should now visible in the graph window.
3. Double-click on the x-axis to access the axis attributes. Change the "Plot vs." field to above expression and "OK" the form.
In reply to Jim McMahon:
Jim, thanks for replying. I tried it and it worked. The timing of your answer was perfect, because I had another school assignment tonight that I needed this answer for. Tonight I actually needed to do the same thing for a transient simulation, and that worked also. For example, I needed to plot Vout vs. Vin for a digital gate using a transient sim. The same method works.